Thank you so much for uploading these images. I have thoroughly analyzed this problem. It is real and happens on all platforms, although it is much more likely to happen on Windows. It happens irrespective of the Bayer pattern selected, when a relatively large number of RAW frames is selected in the Debayer tool.
This problem is complex and difficult to debug. The error originates in the RAW support module, somewhere within LibRaw's code, and happens when LibRaw is being invoked from a running thread. The reason you didn't find it before is that previous 1.8.5 versions of PixInsight used dcraw as a back-end implementation to support digital camera raw formats, while PixInsight 1.8.6 uses LibRaw.
The bug causes an unavoidable application termination as a result of a series of successive critical errors, which leave the code involved in an unstable state that cannot be recovered. That being said, the practical importance of this bug is very limited. The Debayer tool should not be used to demosaic raw frames from digital cameras directly. It is intended to be used on already calibrated frames, which should be in XISF format. Of course, there are no problems at all when you use XISF images with the Debayer tool, since the XISF implementation is fully thread-safe.
So the workaround to this problem is simply to use it as it is intended to be used: with calibrated frames in XISF format. If you don't want to input calibrated frames, you can use the BatchFormatConversion script to convert your ARW files to XISF files, then feed the Debayer tool with them.
Again thank you for detecting this issue. At any rate, I'll try to fix it as soon as possible.
